Field of the Invention
The invention concerns a novel silica sol material for producing biodegradable and/or absorbable silica gel materials having improved properties and also a process for its production and its use. The invention also concerns biodegradable and/or bioabsorbable silica gel fibre materials.
Description of Related Art
Diverse efforts are underway to develop biodegradable and/or bioabsorbable materials for various applications in human medicine and medical technology. These sectors moreover have higher and higher requirements, particularly with regard to the biocompatibility, biological activity and the toxicological properties of the materials.
Absorbable silica gels are known in the prior art. DE 196 09 551 C1 describes biodegradable, bioabsorbable fibrous structures. These fibres are obtainable in a sol-gel process by drawing threads from a spinning dope and drying them where appropriate. The spinning dope comprises one or more partially or completely hydrolytically condensed compounds of silicon which are derived by hydrolytic condensation from monomers of the general formula SiX4. These fibres have the disadvantage that, in a degradation directly after the spinning operation, they do not produce good results in cytotoxicity tests and in some instances have to be rated as cytotoxic. Such toxicity is generally unwelcome for use in human medicine or medical technology, for example in the sector of wound healing. The process for producing the fibres according to DE 196 09 551 C1, moreover, has the disadvantage that the resulting mixture after the removal of the solvent in the hydrolysis condensation step is already a multiphase mixture and has to be subjected to a filtration to remove the solids formed. In addition, the formation of the solid phase and the mandatory filtration step mean that a large proportion of the spinnable sol is lost. Nor does the process of DE 196 09 551 C1 safely suppress the formation of a not inconsiderable proportion of a solid phase, in particular a gel formation, during ripening. This further reduces the proportion of spinnable sol dope.
Irrespective of this, it has been possible to show that the inventive fibres and fibrous nonwoven webs have improved wound healing properties. Furthermore, the inventive fibres and fibrous nonwoven webs are particularly suitable for use as cell support structures.